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U.   S.    DEPARTMENT   OF   AGRICULTURE,, 

BUREAU  OF  ANIMAL  INDUSTRY.— Bulletin  No.  71. 

0.  E.  SALMON,  D.  V.  M.,  Chtef  of  Bureau. 


uiECAMEMBERT  TYPE  OF  SOFT  CHEESE  IN 
THE  UNITED  STATES. 


H.  W.  CONN,  CHARLES  THOM,  A.  W.  BOSWORTH, 
W.  A.  STOCKING,  Jr.,  and  T.  W.  ISSAJEFF. 


Y  OF  CAUFC 
-,S  ANGELES 

SEP  23  1952 


LIBRARY 
WASHINGTON:  qq^    py^S.  PCOM 

GOVERNMENT    PRINTING    OFFICE. 
1905. 


OROAXIZATION  OF  THE  BUREAU  OF  ANIMAL  INDUSTRY. 


Chief:  D.  E,  Salmon,  D.  V.  M. 
AiwhUmt  Chief:  A.  D.  Melvin,  J).  V.  ^. 
Chief  Ckrk:  E.  B.  Jonks,  LL.  :M.,  M.  D. 

Dairy  Divimon:  Ed.  H.  Webster,  M.S.,  chief;  Clarence  B.  Lane,  B.  S.,  assistant 
chief. 

hiitpection  Dii'mon:  A.  iSL  Farki.ncjto.v,  B.  S.,  D.  V.  M.,  chit'f. 

Quarantine  Division:  RicnAun  W.  Hickman.  Pli.  <!..  V.  ^I.  1)..  chiff. 

Ijiiior:  George  F-wettk  Tho.mp80N,  M.  S 

Artist:  W.  S.  D.  Haines. 

Animal  Husbandman:  Georce  M.  Ro.mmel,  B.  S.  A, 

Librarian:  Beatrice  C.  Obekly. 

l.\hokat<)rie.s. 

Bim-heinic  Diii^tion:  Marion  Dorset,  I\L  D.,  chief. 

Pathological  Division:  John  R.  Moiiler,  A.  M.,  Y.  M.  D.,  chief. 

Zoological  Division:  Brayton  H.  Ransom,  B.  Sr..  A.  ">r.,  acting  zoologist. 

experiment  STATKi.N. 
SujicriiitfiKlfnt :  V..  C  ScnROEDER,  M.  D.  V.;  expert  Ji.<.<istaiit,  W.  E.  Cotton. 

inspectors  in  CHARGE. 


Dr.  F.  W.  .\ln.s\vorth,  Union  Stock  Yards,  Pitts- 
burg, I'll. 

Dr.  M.  O.  Anderson,  care  Geo.  A,  Homiel  &  C!o., 
Austin,  Minn. 

Dr.  Don  C.  Ayer,  Post-Office  Building,  South 
Omaha,  Nebr. 

Dr.  G.  S.  Baker,  6th  and  Townsend  .st«.,  San  Fran- 
cisco. Cul. 

Dr.  L.  R.  Baker,  South  St.  J(»seph.  Mo. 

Dr.  Bovd  Baldwin,  care  Cudahv  Bro.s.,  Cndahv, 
Wis. 

Dr.  \.  E.  Behnke,  room  432,  Federal  Building. 
Milwaukee.  Wi.«. 

Dr.  John  A.  Bell,  Watertown,  N.  Y. 

Dr.  S.  K.  Bennett,  room  338,  Live  Stock  Ex- 
change Building,  Knnsn.s  Citv,  KHn.<«. 

Dr.  E.  L.  Bertram,  care  J.  S.  Gilmore,  Davenport, 
Iowa. 

Dr.  Fred  Braginton,  care  Continental  Packing  Co., 
Bloomington,  HI. 

Dr.  J.  J.  Brougham,  care  MLssouri  Stock  Yards, 
St.  Louis,  Mo. 

Dr.  G.  W.  Butler,  care  Dmmmond  Bro.«.,  Eau 
Claire,  Wis. 

Dr.  J.  B.  Clancy,  National  Sto<-k  Yards,  111. 

Dr.  Lowell  Clarke,  room  320,  Qulncy  Building. 
Denver,  Colo. 

Dr.  Charles  Cowie,  Ogdensburg,  N.  Y. 

Dr.  David  Gumming,  912  Lapeer  ave.,  Port  Huron, 
Mich. 

Dr.  Robert  Darling,  care  Cbas.  8.  Hardy,  San 
Diego,  Cal. 

Dr.  E.  T.  Davison,  Rashville,  Nebr. 

Dr.  J.  F.  Deadman,  Snult  Ste.  Marie.  Mich. 

Mr.  Albert  Dean,  room  32>),  Stock  Yard  Staition, 
Kansas  City,  Kans. 


Dr.  F.  L.  De  Wolf,  care  Chas.  Wolff  Packing  Co., 
Topeka,  Kans. 

Dr.  Geo.  Ditewig,  care  Union  Stock  Yards,  Cin- 
cinnati. Ohio. 

Dr.  E.  P.  Dowd,  care  White,  Pevey  «&  Dexter  Co., 
Worcester.  Mass. 

Dr."  ().  E.  Dyson,  316  Exchange  Building,  Union 
.'*to<'k  Yards,  Chicago,  111. 

Dr.  Geo.  C.  Faville,  P.  O.  box  796,  Norfolk,  Va. 

Dr.  J.  W.  Fink,  cure  Swift  &.  (k).,  Harrison  sta- 
tion, Newark,  N.  J. 

Dr.  T.  A.  (Jedde.s,  care  U.  S.  consul,  London,  Edk 
land. 

Dr.  H.  H.  George,  507  John.son  .st.,  Louisville,  K.\ 

Dr.  W.  n.  Gibns,  care  Morton-Gregson  Co.,  Ni 
braskii  City,  Nebr. 

Dr.  L.  K.  Green,  care  Hammond,  Standi.sh  &  Co. 
Detroit,  Mich. 

Dr.  H.  X.  Hedrick,  215  St.  Paul  st.,  Baltimori 
Md. 

Dr.  O.  B.  Hess,  care  Frye-Bruhn  Co.,  Scat  tie.  Wa.'ili 

>fr.  G.  S.  Hickox,  P.  O.  box  1146,  Salt  Lake  Cif 
Utah. 

Dr.  A.  A.  Holcombe,  Aurora,  111. 

Dr.  W.  E.  Howe,  care  Western  I'ucking  Co.,  Den- 
ver, Colo. 

Dr.  Julius  Huel.'ion,  care  Jersey  City  Stock  Yard 
C4>.,  .lersey  City,  N.  J. 

Dr.  F.  W.  Huntington,  U.  S.  customs  office,  G.  J . 
R.  R.  wharf,  Portland.  Me. 

Dr.  Robert  Jay.  care  Jacob  E.  Decker  ak  Son, 
Mason  City.  Iowa. 

Dr.  ft.  A.  Johnson,  Exchange  Building,  Siou 
City,  Iowa. 

Dr.  .iames  Johnston,  care  U.    S.  r<>iisiil!i«<',   ji. 
Chapel  St.,  Liverpool,  England. 


(Concluded  on  third  page  of  cover.) 


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U.   S.   DEPARTMENT   OF   AGRICULTURE, 

BUREAU   OF  ANIMAL   INDUSTRY.— Bulletin   No.  71. 

D.   E.  SALMON,  D.  V.  M.,  Chief  of  Bureau. 


THE  CAMEMBERT  TYPE  OF  SOFT  CHEESE  IN 
THE  UNITED  STATES. 


BY 


H.  W.  CONN,  CHARLES  THOM,  A.  W.  BOSWORTH, 
W.  A.  STOCKING,  Jr.,  and  T.  W.  ISSAJEFF. 


WASHINGTON: 

GOVERNMENT     PRINTING    OFFICE. 
1905. 


LF/ITER  OF  TRANSMirrAL 


U.  S.  Department  of  Ar.RicuLTrRE, 

Bureau  of  Animal  Industry, 

Washington,  D.  C,  March  23, 1905. 
Sir:  T  have  the  honor  to  transmit  herewith  u  manuscript  entitled 
'*  Tile  C'amembert  type  of  soft  clieese  in  tlie  United  States,"  and  to 
reconnnend  its  publication  as  a  bulletin. 

This  paper  represents  the  initiatory  effort  in  a  series  of  cooperative 
experiments  Avhicli  has  been  undertaken  by  the  Dairy  Division  of  this 
Bureau  in  conjunction  with  the  Storrs  (Conn.)  Agricultural  Experi- 
ment Station.  The  full  scope  and  character  of  these  experiments  are 
explained  in  the  introductory  cha])ter  on  the  next  page. 

It  is  anticipated  this  work  will  result  in  much  benefit  to  a  large 
class  of  our  farmers  and  dairymen,  who  may  thus  find  a  new  and 
highly  rennnierative  outlet  for  their  surplus  milk  supply. 
RespectfuUj', 

D.  E.  Salmon, 
Chief  of  Bureau. 
Hon.  James  Wilson, 

Secretary  of  Agriculture. 

2 


INTRODUCTION. 


The  investigations  in  soft-cheese  making  were  undertaken  by  the 
Storrs  Agricultural  Experiment  Station  with  the  hope  »that  there 
might  be  developed  a  new  industry  especially  adapted  to  New  Eng- 
land conditions.  The  Camembert  type  of  soft  cheese  seems  e.spe- 
cially  adapted  to  home  manufacture.  The  process  of  manufacture 
has,  however,  been  held  as  a  trade  secret  and  no  source  of  information 
has  been  available  for  those  who  may  have  desired  to  make  this  type 
of  cheese.  A  series  of  preliminary  studies  was  undertaken,  and  the 
results  gave  promise  of  a  successful  solution  of  the  problems  involved 
and  demonstrated  the  value  of  the  work. 

The  continuation  of  the  investigations,  however,  involved  a  larger 
outlay  than  the  means  of  the  station  would  permit.  Recognizing  the 
wide  value  which  would  result  should  the  experiments  prove  success- 
ful and  a  new  industry  be  established,  a  cooperative  agreement  was 
entered  into  between  the  Storrs  Agricultural  Experiment  Station  and 
the  Dairy  Division  of  the  Bureau  of  Animal  Industry  of  the  United 
States  Department  of  Agriculture,  Washington,  D.  C.  Under  the 
terms  of  this  agreement  a  thorough  study  is  to  be  made  of  the  prob- 
lems involved  in  the  manufacture  of  some  of  the  types  of  soft  cheese 
which  are  so  popular  in  Europe,  but  which  have  been  manufactured 
in  this  country  to  a  very  limited  extent  only. 

The  Storrs  Agricultural  Experiment  Station  has  furnished  the 
necessary  lalniratories,  apparatus,  and  curing  rooms  for  conducting 
the  exjx»riments  and  has  had  tlie  general  planning  of  the  work.  The 
Dairy  Division  of  the  Bureau  of  Animal  Industry  has  furnished 
thret?  exi>orts  to  assist  in  the  work,  namely,  a  mycologist,  a  chemist, 
and  a  j)ractical  cheese  maker,  and  has  provided  for  certain  traveling 
expens<'s  connected  with  the  work.  The  organization  of  the  actual 
working  staff  connected  with  these  investigations  is  as  follows: 

H.  W.  (\)nn,  bacteriologist  of  the  Storrs  Station,  sujMM'visor. 

(Miarles  Thorn,  cheese  exjM'rt  of  the  United  States  I)ej)artment  of 
Agriculture,  mycologist. 

A.  W.  lioswortii,  cheese  expert  of  the  United  States  Department  of 
Agriculture,  chemist. 

ThecKlore  IssajefT,  expert  of  the  United  States  Department  of  Agri- 
culture, cheeseniaker. 

3 


4  INTRODTTCTION. 

W.  A.  Stocking,  jr.,  assistant  bacteriologist  of  the  Storrs  Station. 

In  addition  to  the  foregoing,  who  have  Ihhmi  actively  engaged  in  the 
cheese  investigations,  credit  is  due  to  Dr.  B.  B.  Turner,  chemist  of  the 
Storrs  Station  and  of  the  Connecticut  Agricultural  College,  for  val- 
uable suggestions,  and  to  Mr.  W.  M.  Esten,  lalx)ratory  assistant  to 
Doctor  Conn,  for  bacteriological  determinations.  The  Connecticut 
Agricultural  College  has  freely  permitted  the  use  of  laboratories  and 
api)aratus  for  this  work,  without  which  we  would  have  been  seriously 
handicapped. 

The  work  is  now  thoroughly  organized  and  the  investigations  are 
being  conducted  with  the  following  objects  in  view-  : 

(1)  To  learn  the  details  of  the  methods  of  manufacturing  some  of 
the  soft  cheeses. 

(2)  To  learn  more  accurately  the  details  of  the  process  of  ripen- 
ing, and  to  determine  the  organic  agents  involved  and  their  exact 
functions. 

(3)  To  study  the  chemical  composition  of  the  ripened  product,  the 
changes  involved  in  ripening,  and  their  relation  to  food  values  and 
digestibility. 

(4)  To  discover  the  difficulties  connected  with  the  manufacture  of 
soft  cheese  and  the  ways  of  meeting  them. 

(5)  To  learn  whether  the  manufacture  of  a  first-class  product  is 
possible  in  the  United  States. 

(6)  To  make  public  property  of  all  useful  and  desirable  informa- 
tion upon  the  subject  of  the  manufacture  of  soft  cheese. 

This  bulletin  is  necessarily  preliminary  in  its  nature,  but  it  will  be 
followed  soon  by  others  dealing  specifically  with  the  problems  in- 
volved in  soft-cheese  making  and  how  to  solve  them. 

L.  A.  Clinton, 
Director  Storrs  Agricnltufol  Experiment  Station. 

En.  H.  Webster, 
Chief  of  Dairy  Division^  Bureau  of  Animal  Industry. 


CONTENTS, 


Pace. 

Soft  cheeses  compared  with  hard  cheeses 7 

The  market  for  soft  cheeses  in  the  United  States 8 

Present  market  conditions  of  Camembert  cheese 12 

The  true  Camembert  type 12 

Reasons  for  selecting  Camembert  cheese. 13 

European  literature  consulted 13 

Outline  of  our  method  of  procedure 15 

Ripening  of  Camembert  cheese. ._ 15 

Compendium  of  onr  scientific  investigations 17 

Mycology 17 

Bacteriology l 22 

Chemistry 24 

General  conclusions 26 

Control  of  th3  bacteria  and  molds - 27 

General  summary 28 

Another  report  proposed ^ 29 

5 


ILLUSTRATIONS. 


Page. 
Pl.\te  1.  Fig.  1. — A  board  of  Canioiubert  cheeses.     Fig.  2.— An  improperly 
rii>enetl  Cninenil>ert  cheese;  the  outer  rim  is  li(]uifi(Hl,  while  the 

center  is  hard  sour  curd 17 

2.  A  series  of  Camembert  clieeses.  Fig.  1. — Unrlpened  cheese. 
Fig.  2. — Ilalf-ripened  cheese  with  well-developtMl  moldy  rind. 
Fig.  3. — Che<»se  two-thirds  ripened,  but  witli  central  mass  of 
hard  curd  showing  some  gas  holes.  Fig.  4. — Cheese  nearly 
rii>e  and  so  soft  that  the  upper  tnlge  moveil  be(niuse  of  its 
weight  during  the  exposure 17 

6 


THE  CAMEMBEBT  TYPE  OF  SOFT  CHEESE  IN  THE 
UNITED  STATES. 

Introductory  Paper. 

By  H.  W.  Conn,  Charles  Thom,  A.  W.  Bosvvobth,  W.  A.  Stocking,  Jr.,  and 

T.    W.    ISSAJEFF. 
SOFT   CHEESES   COMPARED   WITH    HARD   CHEESES. 

Hard  cheeses  have  for  a  long  time  been  well  known  in  this  country 
and  have  Ix'on  manufactured  by  our  dairymen  in  large  quantities. 
Until  recently  little  has  been  heard  concerning  another  type  of  cheese 
properly  called  soft  cheese.  This  latter  type,  although  made  from 
curdled  milk,  requires  very  different  methods  of  manufacture,  and 
when  read}^  for  the  table  is  a  totally  different  product.  As  the  name 
indicates,  the  cheese  is  softer,  frequently  so  soft  as  to  be  readily 
spread  upon  bread  like  butter.  But  in  addition  to  this  there  are 
other  striking  differences  Ijetween  the  soft  and  hard  cheeses.  The 
soft  cheeses  are  smaller  than  most  of  the  hard  cheeses.  They  do  not 
keep  well.  Above  all,  their  flavor  is  quite  different,  being  usually 
nuich  stronger.  It  is  a  well -recognized  fact  that  while  cheese  is  a 
valuable  food  Ixjcause  of  the  large  amount  of  protein  it  contains,  nev- 
ertlieless  it  owes  its  chief  popularity  to  its  flavor.  Flavors  are  known 
to  1h'  physiologically  necessary  to  the  proper  digestion  and  assimila- 
tion of  foods.  Hence  the  value  of  highly  flavored  foods  that  give 
relish  to  those  coarser  and  less  flavored  can  hardly  be  overestimated. 
The  soft  cheeses,  with  their  strong  flavors  so  thoroughly  enjoyed  by 
some  people,  have,  therefore,  a  value  decidedly  their  own. 

Tlie  primary  difference  between  the  liard  and  soft  cheeses  is  due  to 
different  methods  of  manii)idati()n  of  the  cunUed  milk.  In  tlie  hard 
cheeses  (Cheddar,  Swiss,  American,  Edam,  etc.)  the  milk  is  curdled 
rather  rapidly  and  the  curdled  mass  subsequently  cut  into  small  pieces 
to  alh)w  much  of  tlie  whey  to  separate  from  the  curd.  Sonu'times  the 
curdled  mass  is  heated  still  further  to  separate  curd  aiul  whey.  After 
this  the  curd  is  placi'd  in  frames  and  subjected  to  a  high  pressure  that 
forces  out  more  of  the  whey,  leaving  a  very  hard  mass  of  tolerably  dry 
curd.  Such  a  curd  ripens  slowly  and  is  not  ready  for  market  for  some 
months,  and  even  when  perfectly  ripe  it  preserves  its  form  and  never 
becomes  very  soft. 

24424-No.  71—05  M 2  7 


8  BUREAU    OF    ANIMAL    INDUSTRY. 

The  st)ft  cheeses — Camembert,  Brie,  Isigny,  Limburger,  Backstein, 
Neufchatel,  cream  cheeses — although  each  is  made  in  a  special  man- 
ner, all  agree  in  one  point,  namely,  the  whey  is  never  fully  drained 
from  them.  The  curdled  milk  is  commoidy  ladeled  into  forms  and 
allowed  to  drain  naturally.  Soft  cheeses  are  not  subjected  to  pressure 
or  heat,  and  therefore  contain  a  larger  per  cent  of  water  at  the  start 
than  the  hard  cheeses.  As  a  conse(juence  of  their  high  water  content 
and  soft  te.xture,  they  aflPord  favorable  conditions  for  the  growth  of 
various  niicr<M)rganisms,  and  enzyme  action  also  occurs  more  readily 
than  in  hard  cheeses.  The  action  of  these  two  groups  of  fermenta- 
tion agents  ripens  the  cheeses  rapidly  and  develops  high  flavors. 
They  are  ready  for  the  table  in  a  few  weeks  instead  of  months,  and 
when  ri|KM)ed  have  not  only  strong  flavors  but  frequently  very  pene- 
trating and  more  or  less  oifensive  odors,  as  in  the  well-known  Lim- 
burger cheese.  Because  of  the  rapidity  of  the  chemical  changes  going 
on  in  tliem,  these  cheeses  are  more  perishable  than  the  true  hard 
cheeses.  Their  marketable  period  is  very  short.  If  placed  upon  the 
table  at  just  the  right  period  they  are  very  apjx^tizing.  If  insuffi- 
ciently ripened  they  do  not  have  the  proper  flavor  or  texture,  and  if 
even  slightly  overripened  they  rapidly  show"  a  tendency  to  decay  and 
are  soon  ruined.  To  place  them  on  the  market  in  such  a  way  that 
they  reach  the  consumers'  table  at  the  proper  stage  of  ripening  is  one 
of  the  difficult  problems  of  the  industry. 

THE  MARKET  iX)R  SOFT  CHEESES  IN   THE   UNITED  STATES. 

The  home  of  these  cheeses  is  continental  Europe.  No  part  of 
Europe  is  "without  its  types  of  soft  cheese.  There  are  several  gen- 
eral tvpes — like  Limburger,  Camembert,  and  Brie — that  are  widely 
distributed  and  made  in  difl'erent  countries,  and  there  are,  in  addi- 
tion, many  local  varieties  with  a  narrower  reputation.  From  their 
centers  of  manufacture  they  are  exported  to  various  cheese-consuming 
countries,  so  that  all  of  the  chief  types  are  generally  found  through- 
out Europe.  Importations  of  soft  cheeses  to  the  United  States  have 
not  lx»en  very  large.  The  American  market  in  the  past  has  been 
almost  monopolized  by  the  hard  cheeses,  principally  of  the  type  of 
the  P^nglish  Cheddar.  Americans  have  known  little  of  the  great 
variety  of  soft  cheeses  common  in  European  markets,  and  there 
has  consequently  been  ver^  little  call  for  them.  AVithin  the  last 
generation  a  moderate  demand  for  soft  cheeses  has  been  developed. 
This  demand  may  be  attributed  partly  to  our  increasing  foreign 
population  and  to  the  desire  of  people  of  European  birth  for  the 
types  of  cheese  familiar  to  them  at  home,  if  is  also  partly  due  to 
the  taste  acquired  by  Americans  who  have  traveled  abroad,  as  well 
as  to  a  growing  appetite  for  them  among  others  who  have  tried  the 


CAMEMBERT    TYPE    OF    SOFT    CHEESE    IN    UNITED    STATES.  V 

new  delicacies.  This  has  led  to  the  importation  of  several  varieties 
of  soft  cheese  to  satisfy  a  market  which  is  increasing  every  year. 
This  importation  has  reached  about  a  million  pounds,  with  a  value 
of  about  $150,000  per  year. 

There  are  many  reasons  why  the  total  importations  have  not  been 
greater.  It  is  difficult  to  import  the  more  delicate  varieties  in  prime 
condition.  Two  weeks  is  the  shortest  period  possible  between  leav- 
ing the  factory  and  reaching  the  retail  market  in  America.  If 
fully  and  properly  ripened  before  shipment  these  two  weeks  cover 
almost  the  entire  marketable  period  of  the  cheese.  To  reach  our 
market  in  condition  for  use  at  all  they  must  be  packed  and  shipped 
before  they  are  in  condition  for  the  table.  In  practice  some  are 
shipped  before  they  are  half  rij^e  or  even  when  the  ripening  has 
just  begun.  The  change  of  conditions  and  entire  lack  of  care  in 
transit  makes  the  resulting  cheeses  which  reach  our  markets  of  very 
uncertain  quality.  It  is  also  difficult  for  the  casual  buyer  to  deter- 
mine when  the  cheese  is  really  ripe.  These  irregularities  furnish 
good  reasons  why  such  importation  is  discouraging  to  dealer  and  to 
consumer  alike. 

On  the  other  hand,  these  conditions  have  stimulated  the  production 
of  certain  soft  cheeses  in  America.  Particularly  is  this  true  of  Lim- 
burger  cheese,  for  which  there  is  a  large  demand.  It  has  been  found 
not  difficult  to  manufacture,  and  it  is  now  made  in  this  country  in  a 
number  of  places  with  a  considerable  degi*ee  of  success.  In  response 
to  a  similar  demand  a  considerable  business  has  arisen  in  the  manu- 
facture of  the  forms  sold  in  our  markets,  as  Brie,  Isigny,  Wiener, 
lunch,  miniature,  etc.,  all  of  which,  though  sold  under  all  sorts  of 
trade  names,  have  a  conmion  type  of  ripening.  Although  the  details 
of  form  and  making  vary  with  the  factory,  the  brand,  and  the  season, 
these  may  be  grouped  together  perhaps  as  the  "American  Brie  "  ty{)e. 
This  American  Brie  tyjx;  nuist  not  be  confused  with  the  Frencli  Brie 
type,  for  the  latter  is  quite  a  different  product.  These  American 
types  have  made  for  themselves  a  large  market  and  may  K'  regank'd 
as  a  fairly  well-established  protluct.  A  preliminiuy  study  of  their 
ripening  process  and  the  factories  in  which  they  are  produced  indi- 
cates, however,  a  very  unsatisfactory  condition.  The  ripening  is  so 
little  imderstood  and  results  are  so  uncertain  that  one  maker  admitted 
that  after  the  cheese  is  made  the  flavor  of  the  product  is  practically 
an  accident  over  which  he  has  no  control.  Some  of  the  cheeses  are 
mined  in  the  ripening  and  the  factories  that  make  them  lose  consider- 
able of  their  product.  It  is  evident,  therefore,  that  the  manufac- 
ture of  the  American  tyjx'  of  these  cheeses  can  hardly  Ih'  regarded 
as  a  success  until  some  means  of  controlling  the  ri|H'ning  can  1m> 
devised  that  shall   reduce  the   failures  and  give  a  more   uniform 


10  BITRKAU    OF    ANIMAL    INDUSTRY. 

produc-t.  Moreover,  tlie  American  tyjMi,  as  Ijcfore  stated,  is  quite  dif- 
ferent from  the  French;  it  is  stronger,  has  a  more  unpleasant  odor, 
and  a  less  delicate  taste.  The  delicate  tasting  Brie  and  Camemlx^rt 
cheeses  are  mostly  imj)oi*ted  from  France.  Up  to  the  present  time 
their  manufacture  has  been  successful  in  but  few  places  in  America, 
and  there  is  a  general  belief  that  their  manufacture  in  this  country  is 
impossible. 

Another  indication  of  the  growing  popularity  of  soft  cheeses  is 
the  large  demand  for  the  varieties  sold  under  various  brands  as 
Neufchatel  and  cream  cheese.  The  basis  for  most  of  these  is  the 
connnon  '"  Cottage  "  or  "  Dutch  "  cheese,  and  many  of  them  are  merely 
sweet  or  sour  curd  put  in  an  attractive  and  appetizing  form.  The 
manufacture  of  these  varieties  is  comparatively  simple,  with  prac- 
tically no  danger  of  loss.  They  are  sold  and  eaten  when  fresh. 
Further,  they  will  yield  a  larger  amount  of  salable  cheese  from  the 
same  quantity  of  milk  than  other  varieties,  and  they  bring  prices 
almost  as  high  as  the  best  imported  cheese.  Very  naturally  these 
cheeses  form  the  basis  of  a  profitable  industry.  But  here,  too,  we 
find  that  the  common  American  product  is  different  from  the  cheese 
in  P^urojxi  going  under  the  same  name.  The  Neufchatel  cheese  of 
Euroi^e  is  a  ripened  cheese,  but  the  cheese  going  by  this  name  in  the 
United  States  is  usually  unripened  curd  with  an  attractive  wrapping. 
Some  of  these  American  products,  however,  are  highly  flavored  and 
compete  favorably  with  certain  ripened  types  that  are  imported.  All 
of  them  command  a  far  higher  price  than  the  ordinary  hard  cheese. 

It  is  certain,  therefore,  that  there  is  an  established  and  rapidly 
growing  market  for  the  l)est  types  of  soft  cheese.  The  profit  in  the 
manufacture  of  the  hard  types  of  cheese  is  exceedingly  small,  both  to 
the  factory  and  to  the  producer  of  milk,  but  the  prices  of  the  highest 
class  of  soft  cheeses  (40  cents  or  more  per  pound)  are  so  much  higher 
than  the  jjrices  of  the  hard  cheeses  that  the  introduction  of  their 
manufacture  should  be  a  great  benefit  to  the  dairymen.  The  fact 
that  soft  cheese  will  not  keep  very  long  gives  an  especial  advantage 
to  the  domestic  over  the  foreign  producers  if  the  products  can  be 
made  of  equal  merit.  For  such  jjcrishable  products  there  is  a  great 
advantage  in  an  intimate  relation  between  the  maker  and  the  con- 
sumer. Factories  near  enough  to  a  large  city  to  supply  the  demand 
with  cheese  always  ripened  to  exactly  the  prime  condition  should 
easily  be  able  to  control  their  home  market  if  they  can  once  control 
their  product.  It  seems  possible  that  there  will  be  an  advantage, 
nearer  the  small  cities  at  least,  in  their  production  by  individual 
dairymen  who  could  dispose  of  their  own  product  in  a  restricted 
market. 

The  great  difficulty  in  the  way  of  the  successful  development  of 
the  soft-cheese  industry  is  in  the  difficulty  of  controlling  the  ripening 


CAMEMBERT   TYPE    OF    SOFT    CHEESE    IN    UNITED   STATES.       11 

SO  as  to  produce  a  uniform  product.  Even  in  the  localities  where 
these  cheeses  are  made  in  Europe  their  treatment  seems  to  be  purely 
b}'^  "  rule-of-thumb  "  methods,  handed  down  as  the  result  of  more  or 
less  successful  experience,  rather  than  by  an  accurate  knowledge  of 
the  reasons  for  the  various  steps  in  the  process.  As  a  natural  conse- 
quence, the  results  are  to  a  large  degree  irregular,  and  utterly  unex- 
plained failures  of  many  kinds  are  familiar  occurrences.  Recognizing 
the  difficulties  in  their  manufacture  in  Europe,  it  is  not  strange  that  the 
troubles  increase  when  attempts  are  made  to  transplant  such  indus- 
tries into  a  new  country,  where  the  practical  rules  applicable  in  the 
old  locality  are  vitiated  by  new  sets  of  conditions,  such  as  atmosphere, 
temperature,  flavors  of  milk,  and  other  factors.  So  great  have  been 
these  troubles  that  there  is  a  belief  that  the  American  product  can 
not  be  made  equal  to  the  imported.  It  is  said  that  the  difference  in 
the  food  which  the  cows  eat  produces  a  differently  flavored  milk, 
thus  making  domestic  cheeses  unlike  those  imported.  Whether  this 
be  true  or  not,  it  is  certain  that  little  success  has  been  reached  by 
American  makers  in  trying  to  reproduce  the  higher,  more  delicate 
gi'ades  of  European  soft  cheese.  When  they  have  succeeded  it  has 
been  by  importing  their  help  from  Europe,  and  in  these  cases  the 
makers  have  carefully  preserved  their  methods  as  trade  secrets.  Even 
in  the  successful  factories  many  failures  occur.  Little  attempt  has 
lieen  made,  apparently,  to  overcome  the  new  difficulties  arising  in  the 
new  conditions.  As  a  result  the  home  product  has  commanded  an 
inferior  price  and  is  less  esteemed  than  the  imported  cheese.  For 
this  reason  the  American  makers  have  disguised  their  goods  by  French 
labels  and  have  not  tried  to  make  a  market  for  an  American  product. 
The  market  varieties  show  great  irregularities.  Complaint  is  con- 
stantly made  by  tlic^. dealer  and  consumer  as  well  that  common  brands 
of  some  of  the  soft  cheeses  are  utterly  unreliable.  In  the  purchase 
of  a  cheese,  except  by  an  expert,  it  is  little  more  than  a  lottery 
whether  it  will  be  mostly  sour  curd  or  might  be  eaten  through  a 
straw.  It  is  clear,  then,  that  although  there  is  a  good  market  for 
uniform  and  reliable  gcxxls,  radical  changes  must  be  made  in  the 
methods  of  production  l)efore  those,  soft  cheeses  will  obtain  the  large 
place  in  the  American  market  which  their  real  merit  deserves.  For 
the  American  dairyman  the  development  of  (his  aluiost  new  industry 
well  deserves  consideration.  It  is  true  that  more  difficulties  are 
involved  in  the  numufacture  of  the  soft  than  of  the  hard  cheeses,  but 
the  returns  are  correspondingly  greater  and  quicker.  Experience, 
however,  in  other  lines  of  dairy  work  shows  that  thorough  scientific 
study  of  the  conditions,  the  problems,  and  the  results  sought  is  usually 
rewanled  by  the  development  of  successful  practical  uiethods  of  con- 
trolling the  entire  prwess.  The  soft  cheeses  will  be  shown  to  Ix'  no 
exception  to  this  rule. 


12  BUREAF    OF    ANIMAL    INDUSTRY. 

PRESENT    MARKET   CONDITIONS   OF   CAMEMBEBT    CHEESE. 

There  is  good  evidence  that  more  than  one  type  of  cheese  is  placed 
upon  our  markets  under  the  name  of  Camembert.  All  of  them  have 
sufficient  similarities  in  texture  and  appearance  to  lead  to  classing 
I  hem  together,  hut  in  flavor  and  odor  they  show  marked  differences. 
Camembert  cheeses  secured  from  different  regions  show  much  varia- 
tion. The  study  of  the  brands  offered  for  sale  in  several  cities  empha- 
sizes an  entire  lack  of  uniformity  among  tliem.  The  stage  of  ripen- 
ing makes  a  marked  difference  in  their  appearance.  One  can  find 
upon  the  same  counter  cheeses  in  which  ripening  has  barely  become 
distinguishable  mixed  with  those  in  every  stage  of  fitness  and  unfit- 
nass  for  use,  even  to  those  which  are  absolutely  putrid,  and  all  are 
likely  to  be  sold  as  in  prime  condition  for  the  table.  Such  cheeses  on 
the  surface  may  l)e  whitish  or  grayish  in  color,  or  yellowish  to  red- 
dish, and  may  be  dry  or  sticky  with  the  accumulation  of  bacterial 
growths.  They  may  l^e  practically  odorless,  or  at  least  inoffensive  to 
smell,  or  they  may  emit  very  objectionable  odors.  These  differences 
are  not  due  wholly  to  the  degree  of  ripeness,  for  cheeses  with  very 
different  appearance  are  often  found  of  the  same  texture  and  flavor 
within.  Moreover,  cheeses  with  almost  identical  surface  appearance 
often  differ  decidedly  in  texture  and  flavor.  The  external  differences, 
we  have  learned,  are  due  chiefly  to  the  different  kinds  of  microorgan- 
isms that  grow  on  the  outside  of  the  cheese,  some  of  which  are  quite 
unnecessary  to  the  production. of  the  desired  ripening.  Consultation 
with  dealers  shows  that  there  is  no  accepted  ideal  among  them  for 
Camembert  cheese;  they  disagree  constantly  on  such  matters.  There 
also  appears  to  be  confusion  in  many  quarters  l)etween  the  types 
known  as  Camembert,  Brie,  and  Isigny.  This  is  probably  due  to  the 
fact  that  the  imported  Brie  is  ripened  in  very  nearly  the  same  way  as 
Camembert,  differing  only  in  size  and  shape  and  details  of  making, 
while  the  type  we  have  discussed  as  American  Brie,  which  includes 
the  cheeses  sold  as  Isigny,  is  very  different  in  its  appearance  and 
ripening  process,  as  well  as  texture  and  flavor.  It  has  been  shown 
that  certain  makers  use  these  names  as  practically  interchangeable — 
that  is,  regard  them  as  the  same  general  type  of  cheese  molded  at 
different  sizes  and  marketable  at  different  degrees  of  ripeness,  and 
sometimes  the  same  cheese  exactly  is  sent  to  market  bearing  different 
labels. 

THE   TRUE   CAMEMBERT  TYPE, 

The  true  Cameml^ert  type  of  cheese  is  that  imported  from  France. 
These  are  shaped  so  that  they  fit  wooden  boxes  about  4^  inches  in 
diameter  and  li  inches  thick.  Upon  the  removal  of  their  wrappings, 
the  cheeses  usually  have  a  rather  firm  rind  about  one-eighth  of  an 
inch  thick  composed  of  interlaced  fungous  threads  supporting  dried 
cheese.     Within,  the  ripe  cheese  should  l)e  a  yellowish  cream  color,  of 


CAMEMBERT   TYPE    OF   SOFT    CHEESE    IN    UNITED   STATES.        13 

a  waxy  or  creamy  texture,  often  almost  liquid  in  age,  and  with  a  dis- 
tinctly characteristic  flavor  that  is  often  not  present  in  some  American 
types,  even  though  they  are  labeled  Camembert. 

REASONS    FOR   SELECTING    CA>IE:^IBERT   CHEESE. 

Camembert  cheese  was  selected  as  the  first  t3q)e  of  soft  cheese  to  be 
studied,  for  several  reasons.  It  is  one  of  the  most  delicate  and  expen- 
sive of  the  soft  cheeses,  selling  on  the  market  usually  for  40  cents  a 
pound.  It  has  been  succesfuUy  produced  by  but  one  large  factory  in 
our  Eastern  States.  A  few  other  factories  have  made  cheese  called 
"  Camembert,"  but  their  product  has  not  made  for  itself  a  place  in 
our  market  in  competition  with  the  imported  varieties.  The  market- 
able period  of  this  cheese  is  so  short  that  the  domestic  brand  should 
have  a  great  adv^antage  over  the  imported.  The  shortness  of  the 
ripening  period — four  to  five  weeks — together  with  the  high  price  of 
the  cheese,  insures  a  good  return  upon  the  investment  and  commends 
its  manufacture  to  the  dairyman  located  too  far  from  the  city  to  sell 
his  milk  as  milk.  Camonibert  cheese  is  already  sufficiently  well 
known  in  this  countp}'  to  insure  the  readj'^  sale  of  any  brand  which 
shows  itself  to  be  always  reasonably  reliable.  Considering  the  lack 
of  uniform  quality  in  the  Camembert  cheeses  seen  on  sale  in  half  a 
dozen  of  the  large  cities  of  the  United  States,  the  wonder  is  not  at  the 
smallness  of  the  demand,  but  that  the  people  will  continue  to  buy  it 
at  all.  Inquiry  shows  that  many  j^eople  are  fond  of  the  cheese,  but 
never  buy  it,  l^cause  they  can  not  depend  upon  the  product.  Dealers 
do  not  like  to  handle  it,  for  the  same  reason.  The  fact  that  local  de- 
man*!  compels  grocers  in  cities,  often  against  their  will,  to  handle  such 
cheeses  is  evidence  that  a  really  goo<l  and  reliable  Camemlx'rt  cheese 
would  make  for  itself  a  large  market.  It  is  readily  seen,  therefore, 
that  the  uiaking  of  this  cheese  ofi'ers  good  possibilities  of  being  a 
profital)le  industry.  The  demand  could  be  more  suitably  met  by 
a  large  niiml)er  of  dairies  or  factories,  each  to  supply  a  limited  terri- 
tory, ratiier  than  that  an  (MU)rnu)Us  (juantity  should  be  pnuluced  by  a 
few  large  concerns.  That  it  requires  special  study  to  overcome  the 
difficulties  of  its  production  In^fore  it  can  l)e  made  by  the  general 
dairyuian  is  also  evident.  For  these  reasons  CamemUM't  cluH'se 
seemed  to  offer  a  most  useful  problem. 

EUROPEAN    LITERATIRK    f'ONSfl-TED. 

When  we  started  the  work  it  was  impossible  to  secure  at  ouce  a 
chees4^  maki'r  who  was  familiar  with  the  factory  manipulation  in  the 
manufa<*tuiv  of  thest»  cheeses.  We  were,  therefore,  obliged  to  work 
from  the  vague  an<l  inadeijuate  descriptions  of  the  details  of  making 
them  published  in  Kiiro|H'an  journals.  Practically  no  detailed 
account  of  the  practice  of  the  In'st  fa<'tories  was  to  l)e  found,  while 
the  few  scientific  papers  avai1abl(>  scarcely  touched  the  practical  prol)- 


14  BUREAU  OF  ANIMAL  INDUSTRY. 

lems.  Our  problem  was  to  imitate  a  market  type  without  any  per- 
sonal knowledge  of  how  it  was  produced.  The  most  extended 
scientific  work  that  had  l)een  published  was  that  of  Epstein,"  who 
made  a  somewhat  careful  study  of  the  bacteria  and  molds  found  in  a 
series  of  rijx*  Camembert  cheeses  and  endeavored  to  determine  which 
were  the  ajronts  of  ripening.  The  conclusion  reached  was  that  the 
ripening  of  Camemlx'rt  cheese  is  produced  by  the  agency  of  bacteria 
alone,  although  he  also  concluded  that  the  ripening  of  Brie  cheese, 
which  is  almost  identical  with  Camembert,  is  aided  by  a  mold. 

In  oj)position  to  this  there  have  been  published  the  results  of  the 
work  of  Roger,''  Avho  also  studied  the  organisms  concerned  in  the 
manufacture  of  Camembert.  He  reached  the  conclusion  that  ripen- 
ing is  produced  by  the  combined  agency  of  a  mold  and  at  least  two 
different  species  of  bacteria.  Roger's  work  has  the  merit  of  having 
been  practically  applied  to  the  manufacture  of  Camemlx'rt  cheese, 
with  results  which  he  claims  have  l)een  very  satisfactory.  But,  on 
the  other  hand,  Roger  has  given  the  public  no  evidence  of  the  work 
he  has  done  to  reach  his  conclusions.  He  has  preferred  to  develop 
the  practical  side  of  his  studies  as  a  trade  secret,  and  has,  therefore,  in 
his  published  articles  withheld  all  details  of  his  experiments  and 
descriptions  of  his  molds  and  bacteria.  Consequently  the  published 
account  of  his  work  is  less  useful  than  that  of  Epstein.  Neither 
worker  has  given  sufficient  data  to  demonstrate  his  claims  or  prac- 
tical methods  of  cheese  making. 

The  fact  that  the  conclusions  of  Epstein  so  totally  disagreed  with 
those  of  Roger  suggested  that  the  subject  at  all  events  demanded 
further  and  more  thorough  investigation.  Moreover,  it  will  be  seen 
in  the  following  pages  that  our  own  results,  in  a  large  measure,  differ 
from  those  of  both  of  these  investigators,  for  we  have  been  able  to 
produce  Camembert  cheese,  typical  both  in  flavor  and  in  texture,  by 
a  method  involving  organisms  essentially  different  from  those  claimed 
by  Epstein  or  Roger  as  the  cause  of  ripening.  It  is  scarcely  possible 
that  the  details  of  either  set  of  experiments  can  be  all  mistakes.  The 
fact  that  three  series  of  studies  upon  the  same  subject  have  reached 
three  quite  different  results  indicates  one  of  two  things:  Either  the 
cheeses  used  in  the  three  series  mentioned  were  of  really  dissimilar 
types,  though  under  the  same  name,  or  a  very  similar  final  product 
can  be  produced  by  different  agents.  Possibly  both  of  these  explana- 
tions are  needed  to  account  for  the  discrepancies.  Certain  of  our 
experiments  have  yielded  information  which" leads  to  the  belief  that 
each  of  the  .three  lines  of  experiment  has  brought  out  part  of  the 
truth.     These  results  will  he  discussed  in  detail  later. 

oArchiv  f.  Hyg.,  Bd.  43.  pp.  1-20;  Bd.  4.'5,  pp.  354-370. 

6  Sep.  pub.  Soo.  Fran.  d'Encore,  Find.  Lalti^re,  1902,  and  Itevue  Hebdoraa- 
dalre,  11,  pp.  327-343. 


CAMEMBERT   TYPE   OF   SOFT    CHEESE    IN    UNITED   STATES.        15 
OUTI.INE   OF   OUR   METHOD   OF   PROCEDURE. 

The  first  problems  which  we  undertook  to  study  were  scientific 
rather  than  purely  practical.  The  reasons  for  this  were  two.  First, 
we  were  unable  at  the  l)e«;innin£^  of  our  work  to  secure  a  cheesemaker 
familiar  with  the  factory  methods  of  making  and  curing  this  type  of 
cheese.  Second,  it  was  not  our  purpose  merely  to  imitate  the  methods 
in  use  in  producing  this  cheese  in  France.  This  would  have  been 
hardly  worth  while  unless  we  could  obtain  a  thorough  understanding 
of  all  the  principles  involved.  It  was  desirable,  therefore,  at  the 
outset  to  conduct  a  series  of  experiments  which  would  bear  directly 
upon  the  determination  of  these  principles,  and  this  could  be  Imst 
done  by  making  a  few  cheeses  under  controlled  conditions.  In  this 
wa}'  we  reached  conclusions  upon  the  problems  involved  which  stood 
the  test  of  practical  experiment  and  which  led  quickly  to  successful 
results  when  cheese  making  was  actually  begun. 

After  securing  the  services  of  Mr.  Issajeff  we  began  the  application 
of  our  scientific  studies  to  the  practical  question  of  cheese  ripening. 
No  description  of  the  practical  method  of  making  and  caring  for 
the.se  cheeses  will  be  given  in  this  introductory  paper.  These  will  be 
given  in  a  later  bulletin  to  follow  shortly.  It  will  be  understood, 
however,  that  the  manufacture  of  CamemlK^rt  cheeses  is  IxMUg  now 
actually  carried  on  at  the  Storrs  Experiment  Station,  and  that  the 
scientific  results  given  here  have  been  actually  applied  to  the  process 
of  manufacture. 

RIPENING    OF    CAMEJIBERT    CHEESE. 

A  brief  outline  of  the  ripening  of  Camembert  cheese  is  as  follows: 
The  rennet  curd  is  fii-st  ladled  into  forms,  filling  them  up  to  a  depth 
of  alwut  T)  inches,  and  is  allowed  to  stand  for  several  liours  for  drain- 
ing. During  this  time  the  curd  settles  until  it  reaches  a  thickness  of 
about  2  inches,  when  the  chee.ses  are  turned  and  allowed  to  stand  in 
the  forms.  During  the  m»xt  twenty-four  hours  the  curd  settles  still 
further,  reaching  a  thickness  of  H  inciies.  The  first  change  atl'ecting 
the  ri|K*ning  is  the  souring  of  the  curd,  which  l)egins  while  the  cheese 
is  in  the  forms.  In  the  course  of  two  days  the  curd  has  U'conie  hard 
and  sour.  The  chet»s<»s  are  then  removed  to  the  ripening  cellar. 
After  a  few  days  in  the  cellar  the  molds  begin  to  grow  ii|)on  their 
surface.  From  this  time  iintil  the  end  of  the  ripening  pei-iod  tluMV 
is  little  visible  external  change  in  the  cheese,  (>xcept  in  the  hixiirijint 
growth  of  molds  and  in  th<'  fact  liiat  during  the  later  stages  of  the 
rip«Miing  there  couunonly  app<'ai's  u|)o!i  the  surface  of  the  cheese  a 
brownish -ret  I  growth,  which  is  likt'ly  to  be  moist  and  slimy,  'i'his 
brownish-red  growth  has  Iweii  regarded  as  a  necessaiv  factor  in  the 
ripening  of  cIum's**,  but  wh<'ther  it  has  any  necessary  connection  with 
it  we  art'  as  yet  uncertain.     During  the  ripening  the  cheeses  at  fii-st 


16  BUREAU    OF    ANIMAL    INDUSTRY. 

l>ocome  somewhat  hard  and  resistant  when  pressed  with  the  finger. 
Later  they  soften  noticeably,  and  when  they  approach  ripeness  they 
auv  qnite  soft  and  yield  readily  to  the  pressure  of  the  finger.  The 
ri|H>ness  is  determined  chiefly  by  the  softne&s  to  the  touch  and  is 
easily  told  by  e.xperience. 

The  riixMiing  changes  are  studied  by  cutting  sections  of  the  cheese 
at  various  stages.  The  photographs  (see  plate  2)  show  such  stages 
of  ripening,  of  which  a  brief  epitome  is  as  follows: 

After  alK)ut  two  weeks  the  acidity  of  the  curd  begins  to  l)e  notice- 
ably less,  especially  at  the  surface,  and  as  the  ripening  progresses 
the  acidit}'  in  time  disappears  so  far  as  indicated  by  the  test  with 
litmus  paj)er.  Meantime  a  change  in  the  texture  of  the  curd  is  evi- 
dent to  the  eye.  Beginning  at  the  outside,  there  appears  a  change  of 
the  hard  curd  into  a  somewhat  softer,  waxy  material.  This  layer  of 
waxy  cheese.  lK?giiniing  at  the  surface,  slowly  extends  toward  the  cen- 
ter and  in  the  course  of  four  to  five  weeks  should  reach  the  center.  In 
half-ripened  cheeses  there  will  be  found  a  layer  of  softened  con- 
sistency on  the  outside,  with  a  central  mass  of  acid  curd  within,  which 
has  not  yet  been  affected  by  the  ripening  agents.  When  the  cheese  is 
completely  ripened  the  softening  extends  to  the  center,  and  the 
whole  cheese,  from  the  outside  to  the  middle,  has  assumed  a  con- 
sistency of  moderately  soft  butter.  \Vlien  in  prime  condition  the 
cheese  is  soft  enough  to  spread  upon  bread  or  crackers,  but  not  soft 
enough  to  run.  An  over-ripened  cheese,  however,  becomes  still  softer 
until  in  time  the  whole  interior  of  the  cheese  below  the  rind  is  con- 
verted into  a  nearly  liquid  consistency,  which  will  run  out  of  the 
cheese  rea<lily  if  the  rind  is  broken.  On  the  other  hand,  an  under- 
ripened  cheese  will  show  more  or  less  of  the  sour  curd  in  the  center 
which  has  not  been  affected  by  the  softening  agents.  The  cheeses  pur- 
chased in  the  market  are  very  frequently  in  one  of  these  two  condi- 
tions, either  overripe  or  underripe.     (See  plates  1  and  2.) 

During  the  ripening  process  there  appears  a  peculiar  flavor  which 
is  characteristic  of  this  type  of  cheese.  This  flavor  is  sometimes  not 
noticeable  until  the  cheese  is  nearly  ripe,  so  that  a  cheese  which  is  two- 
thirds  ripened  may  lack  the  flav^or  in  (piestion.  The  final  result  is  a 
cheest>  with  a  firm,  moldy  rind,  and  with  the  contents  uniformly  soft 
to  the  center,  and  possessing  a  characteristic,  piquant  flavor  which  is 
found  in  this  type  of  cheese  only. 

The  problems  to  he  determined  w'ere  the  causes  of  the  phenomena 
of  ripening,  and  these  are  manifestly  three. 

(1)  The  cause  of  the  original  souring  of  the  curd. 

(2)  The  cause  of  the  decrease  in  the  acid  and  the  gradual  softening 
of  the  curd. 

(3)  The  development  of  the  flavors. 


BUL.  No.  71,  B.  A.  I. 


Plate  1. 


FiQ.  1.— A  Board  of  Camembert  Cheeses. 


Fig.  2.— An  Improperly  Ripened  Camembert  Cheese. 

The  outer  ixtrtion  is  li<iue(ieil,  while  the  center  i.s  liar<1,  t^oUT  eiird. 


BuL.  No.  71,  B.  A.  I. 


A  Series  of  Camembert  Cheeses. 

Fig.  1,  uiiripened  cheese;  t\g.  2.  half-ripened  clieeso  witli  \vell-(levelop)ed  moldy  rind; 
lig. :},  cheese  two-thirds  ripened  but  with  central  nia.ss  of  hard  curd  showing  some  gas 
holes;  fig.  4,  cheese  nearly  ripe  and  so  soft  that  the  upper  edge  moved  because  of  its 
weight  during  the  expMjsure. 


CAMEMBERT   TYPE    OF    SOFT    CHEESE    IN    UNITED   STATES.        17 
COMPENDIUM  OF  OUR  SCIENTIFIC  INVESTIGATIONS. 

Our  work  has  been  developed  along  three  scientific  lines;  the  results 
of  each  line  are  summarized  below.  More  detailed  accounts  of  these 
studies  will  follow  in  separate  papers. 

MYCOLOGY, 

The  constant  appearance  of  mold  in  or  upon  soft  cheeses  such  as 
Roquefort,  Camembert.  and  Brie  has  been  referred  to  already.  The 
works  of  Epstein  and  Roger,  already  discussed,  give  two  views  of  their 
relation  to  the  production  of  cheese.  Epstein  believes  the  mold 
entirely  unnecessary  in  the  production  of  Camembert,  but  notes  its 
pi-esence  and  important  function  in  the  ripening  of  Brie.  Roger, 
on  the  contrary,  believes  the  mold  to  be  really  essential  in  the  ripen- 
ing of  Camembert.  Other  investigations  published  record  the  con- 
stant appearance  of  mold  upon  Brie,  but  give  little  or  no  information 
with  reference  to  Camembert.  Popular  descriptions  of  Camembert 
cheese  factories,  however,  describe  the  constant  presence  of  a  special 
mold  in  the  ripening  cellars.  The  references  to  molds  in  the  litera- 
ture of  the  subject  and  their  constant  presence  upon  the  cheeses  fixed 
for  us  a  series  of  questions:  \\niat  molds  are  associated  with  Cam- 
embert cheese  as  found  in  the  market?  ^^^lich,  if  anj^,  of  these  are 
essential  to  its  proper  ripening?  Exactly  what  changes  jn  the 
ripening  process  result  from  fungous  activity?  What  molds  are 
deleterious?     And  what  is  their  action? 

With  these  questions  in  mind  we  first  made  a  cultural  study  of 
the  flora  of  the  Cameml)ert  cheeses  found  in  the  American  market. 
In  this  about  twenty  molds  were  soon  found,  isolated  in  pure  cul- 
tures, and  descril)ed.  A  more  careful  study  of  our  cultures  with  a 
comparative  examination  of  the  surfaces  of  the  different  kinds  of 
cheese  showed  that  only  a  few  of  these  molds  were  really  common, 
while  but  two  of  them  were  always  present. 

Having  the  organisms  in  pure  cultures,  we  next  undertook  to 
determine  what  relation,  if  any,  each  might  lK>ar  to  the  ripening 
process.  Since  it  is  practically  impossible  to  make  cheeses  entirely 
free  from  other  molds,  or  bacteria,  or  both,  without  changing  their 
chemical  nature,  some  controlled  means  had  to  Ik>  devised  to  study 
the  various  agents  of  ripening  and  the  steps  of  the  process.  We 
found  it  necessary  to  limit  this  conjparative  study  to  the  effects  of  a 
small  group  of  molds.  Thest»  were  grown  in  pure  culture  under 
known  conditions  upon  milk,  ca.sein,  curd,  cheeses,  and  six'cial  media, 
all  so  devised  as  to  determine  separately  tlifferent  |)hases  of  the 
physiological  action  of  the  molds.  For  this  study  we  used  (1)  the 
one  we  shall  call  the  "  CamemlH'rt  mold"   (culture  No.   128);  (2) 


18  BUREAU    OF    ANIMAL    INDUSTRY. 

the  related  sp)ecies  isolated  from  Roquefort  cheese,  which  we  will  call 
the"  Roquefort  mold;"  (3)  one  species  of  Mucor;  (4)  O'idium  lacfis, 
and  sometimes  other  species  of  the  same  genus,  Penicillium.  In  some 
studies  the  list  has  been  extended  to  a  dozen  species  in  each  experi- 
ment, becaust»  with  the  larger  numbers  comparison  of  characters 
gives  a  l>etter  judgment  of  tiie  real  nature  of  the  processes  studied. 

The  souring  ^)f  the  curd  as  a  consequence  of  the  presence  of  lactic 
bacteria  has  already  l>een  descrilnMl  as  the  first  change  after  the  cheest^ 
is  made;  also  the  fact  that  in  Camembertr  cheese  the  lactic  acid  so 
produced  later  largely  disappears,  so  that  when  fully  ripe  such  a 
cheese  commonly  has  an  alkaline  reaction  to  litmus.  This  disap- 
pearance of  acid,  together  with  the  well-known  ability  of  many  molds 
to  reduce  acidity,  has  Ix^en  regarded  as  the  main,  if  not  the  only, 
function  of  the  mold  in  ripening  cheese.  This  view  has  been  widely 
quoted.  Comparative  cultures  of  a  large  number  of  species  show  that 
a  very  large  proportion  of  the  common  molds  an^  able  to  neutralize, 
if  not  decompose,  lactic  acid,  but  they  do  this  in  ditferent  degrees  and 
at  very  different  rates.  The  Camembert  mold  increases  the  acidity  of 
the  medium  during  its  first  few  days  of  growth,  then  changes  and 
reduces  acidity  for  the  remainder  of  the  period  of  activity.  Some 
other  forms  reduce  acidity  from  the  first  and  do  it  much  more  rapidly 
than  this  one.  If  this  were  the  only  function  of  the  mold  in  cheese 
ripening,  many  other  species  should  be  equally  valuable,  or  by  work- 
ing more  rapidly  would  probably  l>e  far  more  effective.  This  part 
of  the  ripening  then  might  be  accomplished  by  any  one  of  a  large 
number  of  forms. 

We  then  turned  our  attention  to  determining  whether  an}'  or  all 
of  these  fungi  acting  in  pure  cultures  possessed  the  power  to  change 
the  hard  curd  to  the  semiliq"iiid  or  viscous  condition  of  the  ripened 
Cameml)ert  cheese.  A  long  series  of  cultures  upon  sterilized  milk, 
milk  agar,  and  sterilized  curd  were  prepared.  Careful  bacterial 
determinations  were  made  to  show  that  the  cultures  were  pure.  From 
these  the  following  facts  appeared :  Sterile  milk  is  slowly  but  almost 
completely  digested  by  nearly  every  specie.s  of  fungus  tried.  Flakes 
of  curd  in  milk  agar  plates  disappear  as  a  result  of  the  action  of  the 
fungi  selected  for  this  experiment.  Masses  of  curd  put  in  flasks  and 
sterilized  in  the  autoclave  until  they  seemed  almost  the  texture  of  rub- 
l)er  became  nearly  completely  soluble  in  water  after  four  to  six  weeks' 
action  of  either  the  Camembert  or  the  R(X|uefort  mold.  P^xperimental 
cheeses  made  from  time  to  time,  with  the  atldition  of  large  quantities  of 
"  lactic  starter  "  to  exclude  other  bacteria,  were  inoculated  with  this 
mold  and  carefully  kept  pure  in  bell  jars.  Under  favorable  condi- 
tions such  chee.ses  assumed  the  texture  of  ripe  Camembert  cheese  in 
from  three  to  five  weeks.  Repeated  analyses  hav^e  shown  that  this  is 
approximately  the  same  kind  of  digestion  as  is  found  in  the  ordinary 


CAMEMBERT   TYPE    OF   SOFT    CHEESE    IN    UNITED   STATES.       19 

Camembert  cheese.  These  pure-culture  experiments  have  thus  shown 
that  this  sjjecies  of  mold  possesses  the  ability  to  change  the  texture  of 
curd  to  the  texture  of  ripe  cheese  in  the  period  of  time  recorded  by 
the  makers  of  such  cheese  as  necessary  for  the  ripening  of  Camembert. 

How,  then,  is  such  a  result  accomplished  ?  Johan-Olsen  in  describ- 
ing the  Swedish  "  Gammelest  "  declares  that  "  he  who  eats  Gamme- 
lest  eats  truly  more  mold  than  cheese."  In  other  words,  he  believes 
that  in  its  ripening  process  the  changes  are  due  to  the  complete  pene- 
tration, of  the  cheese  by  fungous  threads  which  act  directly  to  change 
its  character.  Gammelest  would  then  be  fungus  flavored  with  cheese  ! 
But  cultural  studies  and  careful  microscopic  examination  of  hundreds 
of  sections  fi'om  a  number  of  different  Camembert  cheeses  show  that 
our  problem  is  very  different.  In  Camembert  cheese  the  mold  forms 
a  felted  mass  of  hypha?  upon  the  surface  and  penetrates,  perhaps, 
one-sixteenth  of  an  inch  into  the  curd.  It  never  reaches  even  one- 
third  of  the  distance  to  the  center  of  the  cheese,  while  its  spores  are 
borne  only  upon  the  surface.  This,  together  with  a  very  thin  outer 
layer  of  curd,  constitutes  the  rind  of  the  cheese. 

Furtlier,  our  experiments  referred  to  above  show  also  that  on  sterile 
milk  the  mold  forms  colonies  floating  upon  the  surface  only,  while  a 
mass  of  curd  in  the  bottom  of  the  tube,  fully  2  inches  away  from  the 
nearest  fungous  thread,  may  still  continue  to  be  digested.  It  is  clearly 
impossible  to  attribute  these  marked  digestive  effects  at  such  distances 
to  the  direot  action  of  the  fungous  threads  upon  the  medium.  From 
similarity  to  other  known  processes,  the  presumption  arises  that  thes<5 
are  the  result  of  the  secretion  of  enzymes  by  the  mold. 

To  test  the  validity  of  this  hypothesis,  a  set  of  cultures  were  grown 
for  a  long  time  on  Kaulin's  fluid,  then  examined  by  the  chemist.  The 
presence  of  an  enzyme  capable  of  digesting  proteid  was  satisfactorily 
demonstrated.  We  have,  therefore,  shown  by  pure-culture  methods 
that  the  Camembert  mold  {Pcnuillhim.  cand'idujnf)  is  not  only  capa- 
ble of  changing  the  acidity  of  the  curd,  but  is  able  also  to  cause  such 
changes  of  the  cnrd  as  will  account  for  the  texture  of  the  ripe  cheese, 
and  that  this  result  is  due  to  the  secretion  of  an  enzyme. 

A  cheesei  riix»ne^l  by  this  mold  alone  is  white,  soft,  creamy,  and 
••ntirdy  palatable,  but  is  wanting  in  color  and  completely  lacks  the 
jHM-uliar  flavor  for  which  CanH'nilM'rt  cheese  is  sought  in  the  market. 
After  repeated  tests  had  shown  the  same  result,  we  In'gan  to  "^'ek  for 
sfMue  other  organism  capable  of  producing  the  <lesired  flavt)r.  The 
discovery  of  this  flavor  in  certain  experimental  <'heeses  at  this  time 
was  followe<l  by  their  immediate  microscopic  »'xamination.  which 
showed  the  pres«'nce  of  th«»  s<»cond  of  the  two  fungi  originally  found 
on  CamemlM'rt  cheese.  This  mold,  the  well  known  and  universally 
distributed  (rnl'nnu  (or  Oosportt)  hirtis  had  U'en  discanU'd  from 
nnich  of  our  work  on   ac<(nmt  of  some   failures  and  objectionable 


20  BURKAIT    OF    ANIMAL   INDUSTRY. 

results.  Wo  now  found  that  the  inoculation  of  this  organism  upon 
chtH»ses  partially  ripe  and  lacking  flavor  would  lead  to  the  pro- 
duction of  the  flavor  distinctly  in  a  very  few  days.  Although  from 
its  habits  of  growth  its  development  upon  cheese  is  nearly  always 
accompanied  by  a  rapid  multiplication  of  bacteria,  this  seemed 
good  circumstantial  evidence  that  Oidiuni  lactin  has  something  to  do 
with  the  flavor  of  Camembert  cheese.  Additional  evidence  is  found 
in  the  fact  that  the  examination  of  i)roperly  flavored  ripe  cheese  of 
our  own  make  and  from  the  market  has  never  failed  to  show  its 
presence,  and  it  has  never  been  shown  to  Ix;  present  upon  ripe  cheeses 
without  the  flavor  being  present  also.  The  great  difficulty  surround- 
ing complete  proof  of  the  agency  of  a  particular  organism  in  pro- 
ducing flavor  lies  in  the  fact  that  the  flavors  do  not  begin  to  appear 
until  the  acidity  of  the  curd  is  much  reduced  and  the  digestion 
attributed  in  our  work  to  the  Penicillium  has  advanced  considerably. 
Flavors,  the  chemists  tell  us,  are  associated  with  the  "  end  products 
of  digestion."  A\nien  ripening  has  reached  such  a  stage  as  to  permit 
flavor  formation,  the  grow^th  of  Oidium  upon  the  surface  of  a  cheese 
usually  Ijecomes  complicated  by  the  development  of  surface  bacteria, 
which  becomes  possible  at  about  that  time  on  account  of  the  reduc- 
tion of  the  acidity.  A  final  conclusion  as  to  whether  or  not  Oidium, 
lactis  alone  produces  the  flavor  will  depend  upon  an  exhaustive  test 
of  those  bacteria  so  constantly  associated  with  it. 

The  bacteriologists,  as  will  be  seen  later,  have  shown  that  few 
bacteria,  except  lactic  species,  are  found  within  the  cheese,  and  none 
of  them  seem  able  to  produce  flavor.  The  production  of  flavor  by 
bacterial  action  would  then  depend  entirely  upon  such  bacteria  as 
might  grow  upon  the  surface  of  the  cheese.  In  addition  to  the  evi- 
dences already  mentioned,  it  is  found  that  a  cheese  entirely  covered 
by  a  good  growth  of  the  Camemlxirt  mold  evaporates  water  rapidly 
and  develops  a  hard,  dry  rind,  so  dry  as  to  obstruct  the  entrance  of  bac- 
teria from  without.  In  certain  of  such  cheeses,  into  which  Oidium 
was  inoculated  at  the  time  of  making,  the  characteristic  flavors 
finally  api:>eared,  without  the  association  of  the  reddish  slimj'  surface 
so  commonly  seen.  Further,  many  cheeses  made  and  ripened  entirely 
without  Oidium  lactis  have  in  their  later  stages  become  covered  with 
bacteria,  which  produced  the  surface  appearances  so  often  described, 
but  failed  entirely  to  develop  the  typical  flavor.  In  the  light  of  the 
bacteriological  proof  that  the  interior  of  the  cheese  is  practically  a 
pure  culture  of  lactic  organisms,  the  production  in  some  cases  of  both 
the  flavor  and  texture  of  properly  ripened  Camembert  cheese  without 
a  rich  surface  growth  of  bacteria  is  very  good  circumstantial  evi- 
dence that  Oidium  has  some  function  in  producing  the  flavor. 

A  cheese  inoculated  with  Camemlwrt  Penicillium  will  not  begin  to 
show  delicate  white  threads  of  mold  for  about  three  da  vs.     The  mold 


CAMEMBERT   TYPE    OF   SOFT    CHEESE    IN    UNITED   STATES.       21 

develops  rapidly  from  that  time  until,  by  the  tenth  day  (sometimes  by 
the  seventh  or  eighth),  the  cheese  is  usually  covered  entirely  by  a  pure 
white,  cottony  mass  of  threads  forming  a  layer  possibly  one-eighth 
of  an  inch  deep,  ^^'ith  the  ripening  of  the  spores  or  conidia  the  color 
gradually  changes  to  a  greenish  gi'ay.  This  change  is  completed 
during  the  third  week  usually,  and  no  growth  seems  to  take  place 
afterwards.  During  the  later  stages  of  mold  growth  lai"ge  drops  of 
water  are  excreted  by  the  mold  and  evaporate  from  the  surface.  The 
mold,  therefore,  has  a  rather  definite  period  and  course  of  develop- 
ment. During  that  time  it  seems  to  be  so  thoroughly  adapted  to 
thrive  upon  cheese  as  to  exclude  almost  every  other  form,  but  after  its 
cA'cle  of  development  is  complete  it  may  be  followed  by  other  species 
which,  if  present  l)efore,  are  held  in  check  by  the  more  vigorous 
species. 

One  more  phase  of  the  mold  problem  perhaps  belongs  in  this  pre- 
liminary paper.  Eiforts  have  l)een  made  (o  find  whether  it  is  pos- 
sible to  substitute  other  varieties  or  species  of  the  same  genus  of 
fungi  for  the  one  we  have  l^een  using.  For  such  studies  the  mold 
of  Roquefort  cheese  has  lx?en  carried  as  a  check  upon  our  work  in 
numerous  experiments.  One  other  variety  ol  Penicillium,  differing 
only  in  that  it  never  changes  color,  but  remains  pure  white,  has  boiMi 
tested.  Cheeses  have  been  made  with  these  three  and  several  other 
related  species.  The  Roquefort  Penicillium  grows  strongly  and 
rapidly  upon  cheese,  but  its  presence  always  causes  a  bitter  taste, 
which  remains  pronounced  during  the  jxn'iod  of  four  or  five  weeks 
nece&sary  for  the  ripening  of  Canieml)ert.  So  strong  is  this  effect 
that  the  presence  of  a  colon}'  of  this  mold  less  than  an  inch  in  diam- 
eter may  often  Ik'  detected  by  the  taste  of  the  cheese  *2  inches  away. 
The  pure  white  Penicilliinn  in  its  ordinary  reactions  to  culture  media 
seems  to  l>e  identical  with  the  Camembert  mold,  but  when  tested 
upon  over  one  hundred  cheeses  produced  a  texture  so  entirely  different 
from  it  as  to  make  the  product  entirely  worthless.  It  seems  most  sur- 
prising that  two  forms  so  closely  related  in  structure  and  in  every 
reaction  studied  should  pnxluce  such  different  results  in  cheese  ripen- 
ing. Several  other  forms  have  Ix^en  tried.  Some  produce  pigments 
which  discolor  the  cluH'se;  some  produce  bad  flavors.  A  set  of  four 
species,  although  allowed  to  grow  for  a  |>eriod  of  six  weeks,  pnxhuvd 
no  softening  of  the  curd.  In  two  of  thes«'  cheeses  especially  it  was 
foun<l  that  the  curd  was  still  sour  and  little  changed  less  than  one- 
fourth  of  an  inch  Ih'Iow  the  colonies  of  the  fiingus.  The  four  chtH'se>5 
us<«d  ill  this  <'Xp<M*iinent  IwlongiMl  to  a  set  of  twenty,  sixteen  of  which 
riiMMied  reatlily  in  the  ordiiuiry  way.  Sets  of  clu'eses  made  from  the 
same  milk  and  treated  alike  ripened  (juite  uniformly,  as  a  rule.  Of 
this  set,  H»  ri)H'ni>d  in  the  usual  manner  when  acted  upon  by  Camcm- 
Ijert   Penicillium.     Four  inoculated   with  other  Penicillia   failed   to 


22  BUREAU    OF    ANIMAL    INDUSTRY 

soften.  Such  a  result  shows  that  neitlier  the  molds  used  nor  the 
bacteria  aiul  enzymes  otherwise  present  were  capable  of  producing 
the  texture  of  CaniemlK'rt  in  four  cheeses  of  a  series,  the  remainder 
of  which  were  readily  rijjened  normally. 

-  BACTERIOIXXJY. 

The  universal  presence  of  bacteria  in  all  dairy  products  suggests 
of  course  that  they  may  play  an  important  part  in  the  ripening  of 
cheese.  In  the  various  scientific  accounts  of  Camembert  cheese 
bacteria  are  alwaj's  mentioned,  and  lx)tli  E2)stein  and  Roger  attributed 
to  their  action  a  considerable  part  of  the  rijiening  and  flavor  produc- 
tion. Our  own  preliminary  studies  of  the  market  cheeses  always 
showed  the  presence  of  bacteria  in  great  number  and  in  considerable 
variety.  It  was  manifest  that  most  of  these  wei-e  purely  incidental 
organisms  not  contributing  at  all  to  the  ripening.  In  the  study  of 
these  bacteria  the  following  questions  have  Ijeen  kept  in  mind:  AVliich 
kinds  of  bacteria  are  always  found  and  which  are  only  occasionally 
present?  Which  kinds  of  bacteria  are  present  in  fresh  cheese? 
Which  kinds  of  bacteria  grow  during  the  ripening?  Do  any  of  these 
bacteria  produce  the  Camembert  flavor?  Do  the  bacteria  contribute 
to  the  chemical  changes  that  occur  during  the  rijKMiing?  Part  of 
these  questions  we  have  already  answered,  but  part  of  them  require 
further  study. 

We  fii*st  made  a  bacteriological  study  of  a  considerable  number  of 
ripened  cheeses,  isolating  all  species  of  bacteria  that  could  he  found. 
Except  that  lactic  bacteria  were  always  found,  this  work  gave  no 
significant  results.  AVe  were  somewhat  surprised  to  find  that  the 
group  of  bacteria  that  digest  proteids — the  liquefiers — were  commonly 
entirely  absent.  Inasmuch  as  the  cheese  is  so  evidently  a  digested 
product,  we  had  anticipated  finding  them  in  large  numbers.  This 
absence  in  large  numbers  suggested  that  the  digestive  agent  must  be 
looked  for  elsewhere  than  in  bacterial  action. 

Our  search  for  a  flavor-producing  bacterium  has  hitherto  l^een 
equally  unsuccessful.  Epstein  states  that  by  inoculating  into  a  casein 
.solution  one  of  the  bacteria  he  isolated  from  Cameml)ert  cheese  he 
obtained  a  typical  flavor.  AVe  have  been  unable  to  find  such  a 
bacterium.  We  have  carefully  studied  the  action  upon  milk  of  the 
organisms  isolated  from  cheeses  in  the  hope  of  finding  a  flavor- 
producing  bacterium,  but  have  thui^  far  been  unable  to  find  one.  We 
have,  however,  found  bacteria  that  produce  flavors  that  remind  us 
of  the  American  Brie,  and  of  other  flavors  associated  with  some  sam- 
ples of  cheese,  but  none  that  gave  the  typical  (Camembert  flavor.  We 
are  at  present  inclined  to  think  that  this  flavor  must  be  sought  in 
some  other  line,  as  has  been  shown  in  the  previous  pages. 

The  study  of  the  growth  of  bacteria  in  the  cheese  during  the 


OAMEMBERT   TYPE    OF    SOFT    CHEESE    IN    UNITED    STATES.        23 

ripening  is  very  interesting  and  significant.  We  have  studied  this 
problem  in  cheeses  made  with  and  without  a  hictic  starter.  The 
cheeses  made  with  a  lactic  starter  are  more  uniform  in  ripening. 
Experience  has  shown  that  we  can  with  gi-eater  certainty  obtain  a 
first-class  cheese  if  we  use  such  a  starter.  For  this  reason  the  study 
of  the  bacteria  in  such  cheeses  is  especially  significant.  The  results 
are  very  simple,  for  they  are  an  exact  repetition  of  what  occurs  in 
souring  milk,  as  has  been  already  shown."  At  the  outset  there  is 
commonly  a  small  variety  of  bacteria  present,  which  develop  for  a 
short  time,  but  in  a  few  hours  the  lactic  bacteria  get  the  upper  hand 
and  all  other  species  practically  disappear.  After  about  two  days 
the  cheeses  contain  a  practically  pure  culture  of  lactic  bacteria. 
Thase  increase  in  numbers  until  they  are  about  000,000,000  per  cubic 
centimeter,  and  then  remain  at  about  this  numlx»r  during  the  ripen- 
ing, somewhat  falling  off  toward  the  end.  In  thase  cheeses  there  is 
no  growth  of  liquefying  bacteria  to  which  might  lx>  attributed 
such  digesting  action.  There  are  commonly  a  few  of  these  at  the 
start,  but  they  never  multiply  so  that  they  become  abundant  enough 
to  lead  to  the  supposition  that  they  are  likely  to  play  any  part  in  the 
rijx'ning.  Moreover,  as  mentioned  above,  the  ripening  of  these 
cheeses  proceeds  from  the  surface  inward,  a  fact  that  indicates  that 
the  ripening  agents  are  chiefly  or  wholly  on  the  surface. 

These  facts  are  rendered  more  significant  by  the  bacteriological 
study  of  one  set  of  20  cheeses  that  were  made  without  lactic 
starter.  In  these  cheeses  the  lactic  bacteria  never  obtained  such  a 
complete  ascendency  over  the  other  species  as  where  a  starter  was 
used.  While  they  l^ecame  very  abundant  we  found  that  certain  lique- 
fying bacteria  nndtiplied  and  remained  inconsiderable  numlx»rtothe 
end  of  the  rijx'ning.  The  presence  of  hirge  numlx»rs  of  such  enzyuie- 
protlucing  l)acteria  during  the  ripening  suggests  that  they  may  have 
coutributed  to  the  pnx-ess.  It  was  especially  significant  to  find  (1) 
that  this  cluH'se  ripened  in  the  center  U'fore  it  did  on  the  outer  edge, 
as  would  lx»  expected  if  the  bacterial  enzymes  aided  in  the  ripening, 
and  ('2)  that  the  final  product  was  in  flavor  and  texture  not  very  dif- 
ferent from  the  more  typically  ripened  cheeses.  This  would  seem  to 
suggest  that  while  the  normal  rijx'ning  is  not  <hie  to  the  bacteria  or 
enzymes  in  the  body  of  the  cheese,  bnt  to  the  organisms  on  the  sur- 
face, under  some  circumstances  the  former  may  mat«'rially  contribute 
to  the  pnx'ess,  and  while  pnxlucing  a  somewhat  abnonnal  riix»ning 
will  give  in  the  «'nd  a  similar  resnlt. 

From  the  facts  thus  outlined  we  have  reached  the  conchision  that 
the  bacteria  in  the  Ixxly  of  the  clux'se  are  in  normally  rijxMiing  clux'ses 
concerned  only  in  the  souring  of  the  curd  as  pre|)aratorv  to  the  later 
rhanges.     This  leads  naturally  to  the  study  of  the  organisms  present 

"('onn  and  Ksteii.  Kept.  Storrs  Stii.  r.MH-2. 


24  BUREAU    OF    ANIMAL    INDUSTRY. 

in  the  outer  layers.  This  rind  contains  a  variety  of  molds  and 
bacteria.  The  presence  of  certain  molds  in  the  rind  of  every  Cameni- 
bert  cheese  examined  suggested  from  the  first  that  they  must  be 
imj>ortant  agents  in  the  ripening  process.  This  has  lx»en  demon- 
.strated  in  the  preceding  section,  but  this  rind  also  under  most  cir- 
cumstances contains  many  bacteria.  Our  study  of  these  bacteria 
and  their  actions  is  not  yet  complete.  We  have  as  yet  no  good 
evidence  that  their  action  is  necessary  to  the  production  of  a  first- 
class  product.  That  they  occasionally  modify  the  final  cheese  is 
quite  certain,  and  we  are  also  convinced  that  they  play  an  impor- 
tant part  in  the  ripening  of  the  type  we  have  called  the  "American 
Brie."  Whether  the}'  have  any  influence  on  the  production  of  the 
typical  Camembert  flavor  can  only  be  determined  by  subsequent 
experiments." 

It  should  finally  be  stated  that  the  surface  of  the  ripening  cheeses 
very  frequently  lx?comes  covered  by  an  abundant  growth  of  yeast, 
a  phenomenon  which  the  makers  call  "  sweating."  At  present  we 
have  no  grounds  for  believing  that  this  has  any  influence  upon  the 
rii^ening  unless  it  be  to  check  in  a  slight  degree  the  drying  of  the 
surface  of  the  cheese. 

CHEMISTRY. 

The  chemical  composition  of  a  normal  C^amembert  cheese  is  quite 
well  known,  considerable  work  in  this  line  having  been  done.  This 
work,  however,  is  not  of  much  help  in  studying  the  changes  that  take 
place  during  the  ripening  process  and  makes  it  necessary  to  go  over 
the  same  ground  that  has  l^een  covered  in  the  work  done  on  Cheddar 
cheese. 

The  great  difference  in  the  making  and  ripening  of  Cheddar  and 
Camembert  cheese  soon  made  it  apparent  that  an  entirely  different 
set  of  factors  were  at  work  and  that  the  chemical  side  of  the  inves- 
tigation opened  a  field  which  would  require  con.siderable  time  to 
complete. 

We  have  undertaken  (1)  to  follow  the  chemical  changes  which 
render  the  insoluble  curd  of  a  newly-made  cheese  into  soluble  forms 

a  Since  the  ahove  was  put  in  type  we  have  reoeive<l  from  France  a  set  of 
cheeses  selected  and  forwarded  by  M.  Georges  Roger,  acconipanie<l  l)y  a  letter 
giving  data  as  to  age  and  condition  of  ripeness.  Studies  from  the  surface  of 
these  <'heeses  have  shown  the  presence  of  the  same  renlcillium  we  are  using, 
of  O'idiinn  lartis,  and  of  the  same  si>ecles  of  bacteria  which  api)ear  on  our 
cheeses  and  c<intamination  with  the  same  other  molds  we  have  met.  These 
bacteria  on  the  older  cheeses  formed  n^ldish-brown  slime,  almost  entirely  cov- 
ering the  cheese.  Systematic  tests  of  these  red-slime  protlucing  bacteria  are 
being  made  to  ascertain  what  effect  they  may  really  have  uiK)n  the  ripening  of 
the  cheese.  Cultures  made  from  the  interior  of  the  cheese  showed  practically 
pure  cultures  of  lactic  organisms,  .is  in  our  own  cheese.  These  results  suggest 
that  we  have  the  same  organisms  as  M.  Roger,  though  under  different  names. 


OAMEMBERT  TYPE   OP   SOFT  CHEESE   IN    UNITED  STATES.       25 


found  in  a  cheese  ready  for  consumption ;  (2)  to  isolate  and  study 
the  enzyme  or  enzymes  which  cause  these  changes;  (3)  to  investi- 
gate the  changes  which  concern  the  production  of  the  peculiar  flavor 
which  is  characteristic  of  Camembert  cheese;  and  (4)  to  show  the 
relation  which  each  of  the  constituents  of  a  newly-made  cheese  bears 
to  the  ripening  process. 

Up  to  the  present  time  all  our  attention  has  l)een  given  to  work 
ui>on  the  nitrogen  constituents  of  the  cheese.  This  was  l^ecause  of 
an  early  belief,  confirmed  later  to  some  extent,  that  the  fat  plays  a 
secondary  part  in  the  ripening  and  in  the  development  of  the  flavor 
in  Camembert  cheese. 

The  market  product  was  first  studied  to  establish  a  standard.  This 
was  secured  from  the  analyses  of  a  number  of  imported  cheeses. 
Our  cheeses  compare  favorably  with  these,  yet  we  hope  to  obtain  im- 
provement by  a  slight  modification  in  our  methods  of  making  and  in 
the  handling  of  the  cheeses  in  the  ripening  cellar — that  is,  acidity, 
humidity,  temperature,  and  washing  the  cheeses. 

Table  1. — Chemical  changes  in  the  ripening  of  Camembert  cheese. 


Labora- 
tory No. 

Age. 

Total  ni- 
trogen. 

Nitrogen 
asmono- 
lactate. 

Nitrogen 
as  water- 
soluble. 

Nitrogen 
as  amids. 

Nitrogen 
as  am- 
monia. 

IMiys. 

Per  cent. 

Percent. 

Per  cent. 

Percent. 

Per  cent. 

2r>a 

1 

2.73 

0.40 

o.:fi 

0.23 

o.no 

25b 

3 

2.73 

.41 

.41 

.21 

.00 

26a 

5 

2.81 

.39 

.45 

.21 

.00 

25c 

6 

2.73 

.41 

.54 

.27 

.00 

36b 

7 

2.81 

.39 

.53 

.27 

.00 

37a 

8 

2.92 

.43 

.53 

.26 

.00 

aoc 

10 

2.81 

.67 

.7;^ 

.38 

.Of) 

27b 

11 

2.92 

.62 

.75 

.61 

.00 

2Ha 

12 

2.90 

.63 

.09 

.N.^ 

.00 

27c 

14 

3.92 

.57 

l.ff) 

.48 

.00 

2Hb 

18 

2.90 

.27 

1.76 

.48 

.01 

3»a 

19 

2.65 

.34 

1.59 

.*} 

.02 

2«c 

20 

2.90 

.17 

1.85 

.42 

.06 

a2«b 

21 

2.66 

.13 

1.79 

.48 

.(»5 

14 

28 

2.61 

C) 

2.(W 

.46 

.31 

a  This  series  of  cbeoses  "  went  bad  "  with  bacteria  after  this  samplt^  was  taken.    For  loiuiMiri- 
wm  the  analysis  of  another  cheese,  No.  14,  is  given. 
t>  Not  determined. 

The  first  change  is  the  precipitation  of  the  casein  of  the  milk  by 
rennet.  This  precipitate  or  coagulum  carries  down  with  it  mo.st  of 
the  fat  and  somh'  of  the  milk  sugar.  Tlu-  sugar  is  changed  in  a  few 
days  by  bacteria  into  lactic  acid,  rendering  the  cuni  distinctly  acid 
in  reaction  to  litmus.  The  fat  undergoes  some  slight  changes,  but 
the  pn'cipitated  <asein  underg(H's  a  very  marked  modification. 

Practically  no  change  takes  place  in  the  clu'ese  e.\c<>|)t  the  develop- 
ment of  acid  during  the  first  twelve  (hiys.     Then  the  curd  Iw-gins  to 


26  BUREAU    OF    ANIMAL    INDUSTRY. 

soften  and  is  gradually  changed  from  an  insoluble  lump  into  a  soft, 
creamy  mass  almost  entirely  soluble  in  water.  This  change  starts 
at  the  outside  and  progresses  inward  toward  the  center  until  the 
whole  mass  has  been  acted  upon. 

This  change  in  the  curd  is  probably  due  to  one  or  more  enzymes 
produced  by  the  molds  growing  on  the  cheese.  These  enzymes  lx>gin 
their  activity  at  about  the  fruiting  time  of  the  molds — about  the 
twelfth  day.  They  have  not  l>een  separated  as  yet,  but  tlie  evidence 
at  hand  seems  to  indicate  the  presence  of  both  tr^ptic  and  peptic-like 
enzymes. 

Some  idea  of  the  changes  that  take  place  can  be  obtained  from  the 
table  on  the  preceding  page. 

GENERAL  CONCI-l^SIOXS. 

Although  the  results  of  these  lines  of  work  are  still  incomplete, 
some  conclusions  have  been  reached  which  bear  directly  upon  the 
practical  problems.  These  conclusions  have  been  put  to  the  test  of 
constant  use  since  the  establishment  of  our  ripening  cellar,  and  have 
brought  a  much  l)etter  understanding  of  the  problems  involved  than 
was  before  available. 

It  has  been  conclusively  shown  that  the  making  of  Camemliert 
cheese  is  not  dependent  upon  unique  conditions  obtainable  only  in 
very  restricted  localities,  but  rather  upon  securing  the  i)roper  cultures 
and  conditions,  which  are  possible  almost  anywhere.  Cheeses  made 
at  this  station  have  been  compared  with  the  best  imported  goods 
obtainable  in  America,  and  pronounced  practically  identical,  not  only 
by  memlwrs  of  the  force,  but  by  importers  and  connoisseurs  who  have 
eaten  this  type  abroad.  These  cheeses  are  in  no  way  inferior  in  tex- 
ture or  flavor  to  the  best  market  article.  They  have  l)een  ripened  by 
inoculation  with  pure  cultures  and  have  been  watched  constantly  and 
tested  by  the  bacteriologists,  the  chemist,  and  the  mycologist  at  every 
stage  of  their  ripening.  The  element  of  chance  is  thus  excluded  from 
the  result.  The  organic  agents  involved  are  known.  The  difficulties 
encountered  in  the  attempts  to  establish  this  brand  of  chees(>-niaking 
in  the  past  have,  therefore,  been  due  to  insufficient  knowledge  of  the 
molds  and  bacteria  involved  in  the  process,  rather  than  to  failure  in 
obtaining  any  peculiar  conditions  or  the  proper  milk. 

Our  practical  work  also  proves  that  it  will  be  possible  to  control 
the  riiDcning  to  such  an  extent  as  to  produce  a  more  uniform  product. 
It  has  l>een  the  practice  of  the  makers  in  the  past  to  provide  suit- 
able conditions  and  then,  as  one  has  put  it,  let  '•  nature  do  the  ripen- 
ing." As  a  consequence  of  this  "  hit  or  miss  "  way  of  doing  things, 
some  cheeses  are  inoculated  with  the  proper  cultures  from  the  first, 
some  bear  one  organism  and  not  the  other  necessary,  while  wrong 


CAMEMBERT   TYPE    OF   SOFT   CHEESE    IN    UNITED    STATES.       27 

species  of  bacteria  and  mold  very  commonly  grow  in  or  upon  the 
cheeses,  so  that  the  final  results  are  very  uncertain.  This  accounts 
in  a  large  measure  for  the  variation  in  appearance,  texture,  and 
flavor  of  such  cheeses,  and  is  apparently  responsible  for  the  differ- 
ences between  the  imported  and  xVmerican-niade  types. 

CONTBOL   OF   THE   BACTERIA    AND    MOLDS. 

It  became  evident  very  early  that  uniformity  depends  upon  the  con- 
trolling of  the  growth  of  bacteria  and  molds  from  the  time  the  cheese 
is  made  until  the  close  of  the  ripening.  This  i)ointed  to  inoculation  as 
the  best  means  of  reaching  the  desired  result.  Experience  has  justi- 
fied this  conclusion  at  every  step.  The  use  of  lactic  starters  in  butter- 
making  had  already  established  a  simple  means  of  controlling  the 
development  of  bacteria.  The  control  of  the  molds  was  a  more 
difficult  23roblem,  inasmuch  as  there  are  at  least  two  different  molds, 
and  to  obtain  the  desired  result  depended  upon  keeping  the  proper 
balance  between  these  two  organisms  growing  upon  the  same  surface, 
but  having  different  functions.  AVc  have  learned  that  by  varying 
the  conditions  and  growth  of  the  Penicillium  we  can,  to  a  large 
extent,  control  the  development  of  the  other  mold.  Oidium  will 
not  grow  profusely  upon  a  cheese  already  covered  with  the  white 
mold,  and  by  developing  a  luxuriant  growth  of  the  latter  we  can 
hold  the  former  largel}^  in  check.  Cheeses  in  which  the  Oidium 
has  not  develoi)ed  abundantly  are  either  mild  in  flavor  or  lacking 
entirely  in  the  typical  Camembert  flavor.  We  have  succeeded  in 
producing  cheeses  j)erfectly  ripeued  so  far  as  texture  is  concerned, 
but  flavorless,  others  with  the  flavor  distinctly  developed  but  mild, 
and  others  again  with  a  strongly  developed  Camembert  flavor.  Our 
ex|)eriments  thus  far  seem  to  show  that  by  controlling  the  giowth 
of  these  two  molds  we  can  control  both  ripening  and  flavor  produc- 
tion, although,  as  above  suggested,  we  have  not  yet  absolutely  ex- 
cluded the  possibility  that  bacteria  may  play  some  part  in  the  j)rocess 
of  flavor  j)roduction. 

The  important  practical  problem,  then,  appears  to  be  to  «l(>vise 
methods  of  treatment  that  will  enable  the  cheesemaker  to  control  the 
growth  of  microorganisms,  and  primarily  the  lactic  bact<'ria  and 
two  species  of  molds.  The  control  of  the  fii-st  process  of  souring  of 
thc!  curd  is  very  easy.  It  is  only  necessary  to  ap|)ly  here  the  method 
now  so  widely  used  in  cream  ripening,  namely,  the  inocnhition  of  the 
milk  with  lactic  starters.  Thesi*  starters,  if  placed  in  fresh  milk, 
insure  a  projM'i' souring  with  pci-fect  nnifoi'niity. 

The  conti"ol  of  mold  growth  is  a  more  dillicnlt  matter.  Ix'cause  of 
the  great  likelihood  that  the  checs«'s  in  handling  will  U'conic  inocu- 
lated  on   the  surface   with  other  than   the  desired   organisms.     The 


28  BUREAU    OF    ANIMAL    INDUSTRY. 

solution  of  the  problem,  however,  apijears  to  be  found  in  proper 
iittontion  to  throe  factors. 

( 1 )  The  inoeuhition  of  the  cheese  at  the  proper  stage  with  a  com- 
paratively large  quantity  of  the  spores  of  the  desired  organisms. 
At  just  what  stage  the  inoculation  should  bo  made  and  in  what  way 
we  are  not  at  pi-esent  prepared  to  say.  The  question  of  direct  inocu- 
lation of  cheese  with  two  molds  as  a  means  of  controlling  ripening 
is  an  entirely  new  one  in  the  discussion  of  this  cheese  problem.  The 
practice  of  the  factories  has  been  to  allow  the  cheese  to  develop  the 
proper  mold  after  entering  the  riix^ning  room.  But  there  seems  to 
t)e  a  good  reason  for  a  change  in  this  particular.  Milk  as  it  reaches 
the  factory  already  contains  the  germinating  spores  of  many  species 
of  fungi.  Some  of  these  forms  develop  even  more  rapidly  than  the 
ones  essential  to  our  purpose.  The  proper  mold  has  never  been  found 
by  us  in  thousands  of  cultures  of  milk  as  it  comes  from  the  barn, 
while  undesirable  species  are  very  common.  If  the  Penicillium 
essential  to  cheese  ripening  is  to  take  and  maintain  the  ascendancy 
in  the  ripening  process  it  is  imjjerative  that  it  should  begin  to  grow 
as  soon  as  the  cheese  is  made.  Although  further  experience  is  neces- 
sary to  determine  the  best  time  and  manner  of  the  introduction  of  the 
molds,  we  are  convinced  that  their  early  introduction  gives  advan- 
tages more  than  compensating  for  the  additional  labor  involved. 

(2)  The  cleanliness  of  the  ripening  cellar.  The  cheeses  remain  in 
the  ripening  cellar  from  four  to  five  weeks,  where  the  conditions  are 
kept  ideal  for  mold  growth.  If  the  walls,  shelves,  or  floors  are 
allowed  to  become  covered  with  a  growth  of  miscellaneous  molds, 
their  spores  are  sure  to  reach  the  cheeses  and  are  then  liable  to  jjro- 
duce  trouble.  The  remedy  for  this  is  cleanliness,  and  special  care 
should  l)e  taken  to  prevent  the  growth  of  molds  in  the  ripening  room. 

(3)  The  treatment  of  the  cheese  in  the  cellar.  We  have  learned 
that  variations  in  moisture  and  temperature  of  the  ripening  cellar, 
and  different  methods  of  handling  the  cheeses,  all  greatly  influence 
the  growth  of  the  molds  and  bacteria.  A  perfectly  uniform  method 
of  handling  is  therefore  necessary  for  perfect  uniformity  in  results. 
Differences  in  little  matters  of  detail  are  found  in  the  treatment  of 
cheeses  in  different  factories,  and  these  become  the  basis  of  each 
maker's  brand.  Some  wash  their  cheeses ;  others  do  not.  Some  turn 
them  more  often  than  others.  Some  send  them  to  the  market  in  a 
greener  condition  than  others. 

GENERAL   SUMMARY. 

The  conclusions  we  have  drawn  at  present  are  as  follows: 
1.  The  ripening  of  Camembert  cheese  is  due  to  the  presence  of 
definite  molds  and  bacteria.     It  is  not  merely  a  matter  of  manipula- 
tion and  locality. 


CAMEMBERT   TYPE    OF   SOFT    CHEESE    IN    UNITED   STATES.       29 

2.  One  mold  {Penicillium  candidum?)  produces  the  principal 
changes  in  the  curd  which  gives  the  texture  of  the  normally  rijwned 
cheese.  Another  {O'idium  lactis),  acting  in  conjunction  with  the 
first,  is  necessary  to  produce  the  flavor. 

3.  The  presence  of  lactic  bacteria  (conmionly  used  in  the  form  of  a 
starter)  produces  the  necessary  acidity  of  the  curd  and  prevents 
further  bacterial  a(;tion  within  the  body  of  the  cheese. 

4.  No  other  organisms  seem  absolutely  necessary  to  produce  the 
texture  and  flavor  of  Camembert  cheese,  though  other  species  of 
bacteria  are  always  present  in  or  on  the  cheese. 

5.  It  is  possible  so  to  control  the  process  of  ripening  as  to  produce 
such  results  with  reasonable  uniformity. 

6.  It  is  perfectly  practicable  to  produce  first-class  Camembert 
cheese  in  the  United  States. 

ANOTHER    REPORT   PROPOSED. 

In  this  introductory  paper  only  the  general  principles  can  be  out- 
lined, and  we  hope  to  follow  this  paper  soon  with  another  which 
will  give  in  detail  the  actual  methods  of  making  and  handling  which 
we  have  found  most  successful  in  producing  the  best  product. 


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